Allowance for Loan Losses and Credit Quality of Loans, Troubled Debt Restructurings (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013 Contract	Dec. 31, 2012 Contract
Financing Receivable, Modifications [Line Items]
Period of sustained repayment performance for nonperforming TDRs to be returned to performing status (in months)	6 months
Business Banking [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts		1
Pre-modification outstanding recorded investment		$ 0.1
Home Equity [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	23	18
Pre-modification outstanding recorded investment	1.0	0.9
Commercial Loans [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	4	4
Pre-modification outstanding recorded investment	7.0	6.6
Residential Real Estate Mortgages [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	6	12
Pre-modification outstanding recorded investment	0.5	1.2
Subsequent Default [Member] | Home Equity [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	8	1
Pre-modification outstanding recorded investment	0.4	0.1
Subsequent Default [Member] | Commercial Loans [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	1
Pre-modification outstanding recorded investment	0.9
Subsequent Default [Member] | Residential Real Estate Mortgages [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts		2
Pre-modification outstanding recorded investment		$ 0.3